What are the recommended trails and management strategies for patients undergoing Coronary Artery Bypass Grafting (CABG)?

Recommended Trials and Management Strategies for CABG Patients

Key Clinical Trials Referenced in CABG Guidelines

The major randomized trials that inform current CABG practice include GABI (German Angioplasty Bypass-Surgery Investigation), MASS (Medicine, Angioplasty, or Surgery Study), and TRITON-TIMI 38, which established the evidence base for comparing CABG to medical therapy and PCI, as well as perioperative antiplatelet management. 1

Historical Landmark Trials

• GABI and MASS trials compared CABG versus PCI and medical therapy, demonstrating CABG's superiority in multivessel disease for symptom relief and survival in specific anatomic subsets 1
• TRITON-TIMI 38 established prasugrel's bleeding risk profile in CABG patients, showing higher CABG-related major bleeding compared to clopidogrel 1
• PLATO trial compared ticagrelor versus clopidogrel, finding similar bleeding rates when CABG was performed after drug discontinuation 1

Perioperative Antiplatelet Management Strategy

Aspirin Protocol

Administer non-enteric-coated aspirin 81-325 mg daily preoperatively to all CABG patients, as this reduces operative morbidity and mortality with only modest bleeding increase. 1

• Continue aspirin through surgery without interruption 1
• Reinitiate aspirin 100-325 mg within 6 hours postoperatively and continue indefinitely 2

P2Y12 Inhibitor Management

For elective CABG:

• Discontinue clopidogrel and ticagrelor at least 5 days before surgery 1
• Discontinue prasugrel at least 7 days before surgery 1

For urgent CABG:

• Discontinue clopidogrel and ticagrelor at least 24 hours before surgery to reduce major bleeding 1
• Surgery may be performed less than 5 days after clopidogrel/ticagrelor discontinuation and less than 7 days after prasugrel discontinuation when urgency outweighs bleeding risk 1

Critical timing consideration: CABG performed <24 hours after clopidogrel discontinuation significantly increases major bleeding risk, while surgery 1-4 days after discontinuation increases transfusion requirements but not life-threatening bleeding 1

GP IIb/IIIa Inhibitor Management

• Discontinue eptifibatide or tirofiban at least 2-4 hours before surgery 1
• Discontinue abciximab at least 12 hours before surgery 1

Beta-Blocker Protocol

Administer beta-blockers for at least 24 hours before CABG to all patients without contraindications, as this reduces postoperative atrial fibrillation incidence and clinical sequelae. 1, 2

• Reinstitute beta-blockers as soon as possible postoperatively 1, 2
• Prescribe beta-blockers at hospital discharge to all patients without contraindications 1
• Preoperative beta-blockers in patients with LVEF >30% reduce in-hospital mortality 1
• In patients with systolic heart failure undergoing CABG, beta-blockers reduce in-hospital mortality from 5.20% to 2.03% and 30-day mortality from 6.16% to 2.98% 3

Conduit Selection Strategy

Use the LIMA to bypass the LAD artery in all patients without contraindications, as this is the single most important factor for improving long-term survival. 1, 2

Arterial Graft Hierarchy

• First priority: LIMA to LAD (Class I recommendation) 1, 2
• Second priority: Radial artery for the second most important stenosed non-LAD vessel instead of saphenous vein to improve long-term cardiac outcomes 2
• Consider bilateral IMA grafting in appropriate patients by experienced operators for improved long-term outcomes 2

Specific Conduit Recommendations

• Use right IMA to bypass LAD when LIMA is unavailable or unsuitable 1
• Consider second IMA for left circumflex or right coronary artery when critically stenosed and perfusing LV myocardium 1
• Use radial artery grafts for left-sided arteries with severe stenoses (>70%) and right-sided arteries with critical stenoses (>90%) 1
• Avoid arterial grafts for right coronary artery with <90% stenosis 1

Saphenous Vein Graft Limitations

• SVGs have declining patency over time, with 10-25% occluding early 1
• Radial arteries demonstrate superior long-term patency compared to saphenous veins 2

Perioperative Monitoring Requirements

Electrocardiographic Monitoring

Perform continuous ECG monitoring for arrhythmias for at least 48 hours after CABG in all patients. 1, 2

• Continuous ST-segment monitoring for ischemia detection is reasonable intraoperatively 1
• ST-segment monitoring may be considered in early postoperative period 1

Hemodynamic Monitoring

Place pulmonary artery catheter before anesthesia induction in patients with cardiogenic shock undergoing CABG. 1, 2

• PAC placement is useful intraoperatively or early postoperatively in patients with acute hemodynamic instability 1
• PAC may be reasonable in clinically stable patients after considering baseline risk, planned procedure, and practice setting 1

Cerebral Monitoring

Use intraoperative cerebral oxygen saturation monitoring (near-infrared spectroscopy) to guide anesthetic decisions and prevent postoperative neurocognitive dysfunction. 2

• Routine intraoperative monitoring of processed EEG for cerebral hypoperfusion detection has uncertain effectiveness 1

Glycemic Control Protocol

Maintain blood glucose ≤180 mg/dL using continuous intravenous insulin postoperatively to reduce deep sternal wound infections and adverse events. 1, 2

• Target intraoperative blood glucose <140 mg/dL has uncertain effectiveness 1
• Avoid hypoglycemia while maintaining tight glycemic control 1

Lipid Management

Administer statin therapy to all CABG patients unless contraindicated, targeting LDL cholesterol <100 mg/dL with at least 30% reduction. 1

• Continue statin therapy perioperatively without interruption 1
• Do not discontinue statin or other dyslipidemic therapy before or after CABG in patients without adverse reactions 1

ACE Inhibitor/ARB Management

Continue ACE inhibitors or angiotensin-receptor blockers given before CABG, though the safety of preoperative administration in patients on chronic therapy is uncertain. 1, 2

• The safety of initiating ACE inhibitors or ARBs before hospital discharge is not well established 1

Emergency CABG Indications

Emergency CABG is indicated for:

• Failed primary PCI with persistent ischemia of significant myocardium and/or hemodynamic instability 1
• Postinfarction mechanical complications (ventricular septal rupture, papillary muscle rupture, free wall rupture) 1
• Cardiogenic shock in suitable candidates irrespective of time interval from MI 1
• Life-threatening ventricular arrhythmias with left main stenosis ≥50% or 3-vessel CAD 1

Emergency CABG After Failed PCI

Indications include:

• Acute or threatened vessel closure 1
• Coronary arterial dissection 1
• Coronary arterial perforation 1
• PCI equipment malfunction (stent dislodgement, fractured guidewire) 1

High-risk patients for emergency CABG after failed PCI:

• Evolving STEMI 1
• Cardiogenic shock 1
• 3-vessel CAD 1
• Type C coronary lesions (≥2 cm length, excessive tortuosity, extreme angulation, total occlusion >3 months, friable degenerated SVG) 1

Factors increasing perioperative morbidity/mortality in emergency CABG:

• Depressed LV systolic function 1
• Recent ACS 1
• Multivessel CAD and complex lesion morphology 1
• Advanced patient age 1
• Absence of angiographic collaterals 1
• Prolonged time delay to operating room 1

Off-pump CABG in emergency settings may reduce renal failure, intra-aortic balloon use, and reoperation for bleeding. 1

Anesthetic Management

Direct anesthetic management toward early postoperative extubation and accelerated recovery in low- to medium-risk patients undergoing uncomplicated CABG. 1

• Use volatile halogenated anesthetics with opioid supplementation as standard approach 1
• Avoid long-acting neuromuscular blockers like pancuronium, which delay extubation 1
• Optimize coronary perfusion determinants (heart rate, diastolic/mean arterial pressure, ventricular end-diastolic pressure) to reduce perioperative ischemia and infarction 1

Cardiac Rehabilitation

Cardiac rehabilitation is recommended for all eligible patients after CABG, as it increases exercise tolerance by 35%, increases HDL cholesterol by 2%, and reduces body fat by 6%. 1

• Begin early ambulation during hospitalization 1
• Initiate outpatient prescriptive exercise training 4-8 weeks post-CABG 1
• Provide education sessions 3 times weekly for 3 months 1
• Rehabilitation reduces per capita hospitalization charges by $739 over 21-month follow-up 1

Depression Screening and Management

Screen for depression before discharge, as major depressive disorder increases cardiac event risk 3-fold after CABG. 1

• Cognitive behavior therapy or collaborative care reduces objective depression measures 1
• Telephone-delivered collaborative care for 8 months improves quality of life and physical functioning 1
• Both collaborative intervention and cognitive behavior therapy effectively treat post-CABG depression 1

Smoking Cessation

Provide in-hospital educational counseling and offer smoking cessation therapy to all smokers during CABG hospitalization. 1

• The effectiveness of pharmacological smoking cessation therapy before discharge is uncertain 1

Quality Measures

All cardiac surgery programs must participate in state, regional, or national clinical data registries and receive periodic risk-adjusted outcome reports. 1, 2

Critical Pitfalls to Avoid

Do not discontinue beta-blockers perioperatively unless specific contraindications exist, as this increases mortality and atrial fibrillation. 2

Avoid excessive fluid removal during cardiopulmonary bypass (>30 ml/kg ultrafiltration), as this causes hypernatremia and intestinal inflammation. 2

Do not use saphenous vein grafts when radial artery is available for non-LAD vessels, as radial arteries have superior long-term patency. 2

Do not perform emergency CABG after failed PCI in the absence of ischemia or threatened occlusion. 1

Avoid emergency CABG when revascularization is impossible due to target anatomy or no-reflow state. 1